JPH0815583A - Dust adhesion preventive type optical sensor - Google Patents

Abstract

PURPOSE:To prevent malfunction of an optical sensor by adhesion of dust or oil, etc., to the surface of the light emitting element and light receiving element of the optical sensor. CONSTITUTION:The light emitting part 1 and light receiving part 2 of the optical sensor are mounted in an armor 5 which is hollow and is opened at the front surface. A device for introducing compressed air into this arbor is installed at part of the armor 5 so that the compressed air introduced therein is blown out of the front surface aperture of the armor. Both systems of the integrated optical sensor integrated with the light emitting part 1 and the light receiving part 2 and the sepn. type optical sensor separated with these parts are realized by the same constitution. As a result, the stable operation of the optical sensor is assured even in a dusty environment. The frequencies of maintenance operations are decreased and the time thereof is shortened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical sensor, and more particularly to an optical sensor having a structure in which dust, oil or the like is prevented from adhering to the surfaces of the light emitting portion and the light receiving portion of the optical sensor. .

[0002]

2. Description of the Related Art A conventional technique will be described with reference to FIGS. FIG. 3 is a perspective view of a light emitting and receiving integrated type optical sensor, FIG. 4 is a perspective view of a light emitting and receiving separated type optical sensor, and FIG. 5 shows a circuit configuration of the light emitting and receiving of the optical sensor, and FIG. Is a photo transistor for the light receiving element,
Further, FIG. 5B is a circuit diagram in which a photodiode is used for the light receiving element.

The structure of the conventional integrated optical sensor 120 is as follows.
As shown in FIG. 3, the light emitting portion 1 and the light receiving portion 2 are fixed to the front surface 16 of the outer casing 15 with the light emitting surface and the light receiving surface exposed, and the light emitting portion 1 and the light receiving portion 2 are attached from the rear surface 17 of the outer casing 15. There is a code 9 for transmitting the electric signal of. The exterior 15
Is attached to the fixing member 6 and fixes the integrated optical sensor 120 at a setting place.

Next, the operation of the integrated optical sensor 120 will be described. As shown in FIG.
And the integrated optical sensor 120 is set to an operating state. When the object to be measured 20 moves on the conveyor 30 in the direction of the arrow La and crosses the front of the integrated optical sensor 120 fixed to the conveyor table 31, the light 3 emitted from the light emitting unit 1 hits the object to be measured 20. The reflected light 4 is detected by the light receiving section 2 and the measurement target object 2 is detected.
It recognizes 0.

As shown in FIG. 4, the separation type optical sensor 130 comprises a pair of a light emitting unit 130A and a light receiving unit 130B. The light emitting unit 1 is fixed to the light emitting unit 130A with the light emitting surface exposed on the front surface 16 of the exterior 15,
Similarly, in the light receiving unit 130B, the light receiving portion 2 is fixed to the front surface 16 of the outer casing 15 with its light receiving surface exposed, and the cord 9 for transmitting an electric signal is output from the rear surface 17 of each outer casing 15. . The outer casings 15 are attached to the fixing members 6, respectively, and fix the separation type optical sensor 130 at a setting place.

Next, the operation of the separation type optical sensor 130 will be described. As shown in FIG. 4, the fixing type member 6 is fixed so as to face the conveyor table 31, so that the separation type optical sensor 130 is in an operating state. Will be set to. A pair of light emitting units 1 fixed to face the conveyor table 31.
When the measurement target object 20 travels in the direction of the arrow La and crosses between the 30A and the light receiving unit 130B on the conveyor 30, the emitted light 3 from the light emitting unit 1 of the light emitting unit 130A is blocked by the measurement target object 20, Light receiving unit 130B
The light does not reach the light receiving section 2 of the above, and the non-input state is detected to recognize the measurement target object 20.

The light emitting circuit and the light receiving circuit of the optical sensor will be described with reference to FIG. The circuit of FIG. 5A uses a phototransistor PTr42 as a light receiving element. The light emitting circuit has a configuration in which a resistor Re45 and a light emitting diode LED43 are connected in series from a power source and grounded via a transistor Tr40, and the light emission of the LED43 is controlled by the Tr40.

The light receiving circuit includes a power source, a PTr 42 and a resistor Rb.
46 is connected in series and grounded, and receives light from the light emitting unit 1 which is intermittent when the measurement target object 20 moves in the direction of the arrow La at the base of the PTr 42 and corresponds to the intermittent light. The generated current is passed through the resistor Rb46, and the terminal 48
To generate a detection voltage.

In FIG. 5B, a photodiode PD44 is used as a light receiving element, and the light emitting circuit is the same as that in FIG. The light receiving circuit has a configuration in which a PD 44 and a resistor Ra46 are connected in series from a power source and grounded, a PD44 output terminal is connected to a base of a transistor Tr41, and a resistor Rb46 serving as a load is connected between an emitter of the Tr41 and a ground. There is.

The PD 44 receives the light from the light emitting section 1 which is intermittent when the object to be measured 20 moves in the direction of the arrow La,
A current corresponding to the intermittent light is passed through the resistor Ra47 and Tr
It is input to the base of 41 to generate a detection voltage at the terminal 48. Although FIG. 5 shows a circuit that detects transmitted light, a circuit that detects reflected light is also configured by the same circuit.

The light emitting portion 1 and the light receiving portion 2 of the above-described optical sensor have a structure in which light is condensed by condensing light with an optical fiber and an optical lens in addition to the light emitting / receiving element such as a light emitting diode, a phototransistor or a photodiode. There is.

[0012]

The conventional optical sensor does not take measures against the adhesion of dust or oil to the light emitting portion and the light receiving portion. Especially, the optical sensor is used in a factory where dust or oil is scattered. In this case, there is a risk of malfunction, so it is necessary to frequently perform maintenance work, and it is also necessary to pay attention to the installation location of the optical sensor. Therefore, the present invention is intended to prevent dust or oil from adhering to the light emitting portion and the light receiving portion, prevent the occurrence of detection errors, and shorten the maintenance time of the optical sensor.

[0013]

SUMMARY OF THE INVENTION The present invention was devised to solve the above-mentioned problems, and provides a hollow outer casing that covers the light-emitting portion and the light-receiving portion of an optical sensor, and further has the above-mentioned outer casing. A device for introducing compressed air into the interior of the exterior is attached to a part of the exterior, and air is blown out from the opening of the exterior to prevent adhesion of dust or oil or dew condensation.

[0014]

With the configuration described above, dust or oil does not adhere to the surfaces of the light emitting portion and the light receiving portion of the optical sensor due to the air blown out from the opening of the exterior.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dust adhesion preventing optical sensor according to the present invention will be described with reference to FIGS. FIG. 1 shows a dust-prevention type light emitting and receiving integrated type optical sensor, which is shown in FIG.
FIG. 1 is a perspective view of an optical sensor, FIG. 1B is a perspective view showing a usage state, and FIG. 2 is a perspective view of a dust-adhesion-preventing light emitting / receiving separating type optical sensor. The same components as those in the conventional example are designated by the same reference numerals and the description thereof will be omitted.

First, the integrated optical sensor 10 according to the present invention.
In the configuration of 0, the light emitting portion 1 and the light receiving portion 2 are housed inside a hollow exterior 5 as shown in FIG. 1 (a), and the light emitting surface and the light receiving surface are in the direction of an open front surface 16. Exposed. Also, the rear surface 17 is closed and the cord 9 for transmitting an electric signal is projected.

A compressed air tube 8 for introducing compressed air is attached to the cylindrical side surface of the outer casing 5 via an air blowing amount adjusting device 7, and an compressed air is introduced into the outer casing 5 from an air compression device (not shown). Is sent in and air is blown out from the opening on the front surface of the exterior 5. Further, the exterior 5 is attached to the fixing member 6 and fixes the integrated optical sensor 100 at a setting place.

The operation of the integrated optical sensor 100 will be described. As shown in FIG.
Is fixed to the conveyor table 31, the integrated optical sensor 100 is set to the operating state. Conveyor stand 31
When the measurement target object 20 moves in the direction of arrow La and crosses the front of the integrated optical sensor 100 fixed to the conveyor 30, the emitted light 3 from the light emitting unit 1 of the integrated optical sensor 100 is measured. The object 20 to be measured is recognized by reflecting on the object 20 and detecting the reflected light 4 by the light receiving unit 2.

In the measurement state, as described above, the sent compressed air flows out as the blown air 10 from the opening of the front surface 16 of the exterior 5, blows out dust and oil floating in the air, and emits light. Also, it is prevented from adhering to the light receiving section 2.

Next, the separation type optical sensor 11 according to the present invention.
As shown in FIG. 2, 0 is a pair of a light emitting unit 110A and a light receiving unit 110B. The light emitting unit 110A has a light emitting portion 1 and the light receiving unit 110B has a light receiving portion 2 having a hollow shape. A front surface 16 that is housed inside the exterior 5 and that has a light emitting surface and a light receiving surface open
Is exposed in the direction of. Although not shown in the figure, the light receiving portion 2 has a shape similar to that of the light emitting portion 1 in view of the perspective angle. Also, the rear surface 17 is closed and the cord 9 for transmitting an electric signal is projected.

A compressed air tube 8 for introducing compressed air is attached to the cylindrical side surface of the outer casing 5 via an air blowing amount adjusting device 7, and compressed air is introduced into the outer casing 5 from an air compression device (not shown). Is sent in and air is blown out from the opening on the front side of the exterior 5. Further, the air blowing amount adjusting device 7 may be provided on the rear surface 17 and the compressed air may be introduced from there. Further, the light emitting unit 110
A and the light receiving unit 110B are respectively mounted on the fixing member 6 to fix the unit at a setting place.

The operation of the separation type optical sensor 110 will be described. The separation type optical sensor 100 is set in an operating state by fixing the fixing members 6 on both sides of the conveyor table 31 so as to face each other coaxially. When the measurement target object 20 moves in the direction of arrow La and crosses between the pair of light emitting units 110A and light receiving units 110B fixed on both sides of the conveyor table 31, the light emitting unit 1 of the light emitting unit 110A. The emitted light 3 from is blocked by the measurement target object 20, the light does not reach the light receiving unit 110B, and the non-input state is detected to recognize the measurement target object 20.

Even in the measurement state of the separation type optical sensor 110, as described above, the compressed air sent into each unit flows out from the opening portion of the front surface 16 of the exterior 5 as the blown air 10 and enters the air. It prevents dust and oil from floating and sticking to the light emitting unit 1 and the light receiving unit 2. Of course, an inert gas such as nitrogen gas may be used instead of the compressed air.

Further, the separation type optical sensor 110 has both the light emitting unit 110A and the light receiving unit 110B installed on one side of the conveyor table 31 to detect the reflected light from the object 20 to be measured, like the integrated type optical sensor 100. It can also be used in the form.

The circuit configuration of the optical sensor according to the present invention is the same as that shown in FIG. 5 described in the conventional example, and this figure shows an example of a circuit for detecting transmitted light, but it detects reflected light. As a matter of course, the same circuit may be used. A semiconductor laser may be used as the light emitting element instead of the LED 43.

The present invention is effective not only when used in the above-mentioned environment, but also when used outdoors such as for agriculture. Further, it can be used in water or oil, and in this case, it is reasonable to use water or oil as the pressurized transparent fluid instead of the compressed air field.

[0027]

As described above, according to the present invention, it is possible to prevent dust, oil, or the like from adhering to the surfaces of the light emitting portion and the light receiving portion of the optical sensor, and eliminate the detection error of the object to be measured due to this cause. And the effect is great.

The stable operation of the optical sensor can be ensured even in an environment with a lot of dust or oil, and the maintenance time of the optical sensor can be shortened and the frequency of the operation can be reduced. It is possible to select freely regardless of work.

[Brief description of drawings]

FIG. 1 is a perspective view of an optical sensor according to the present invention, which is a dust-adhesion-preventing light-emitting and light-receiving integrated optical sensor,
(B) is a perspective view showing a usage state.

FIG. 2 is a perspective view of a dust-adhesion-preventing light emitting / receiving separating type optical sensor according to the present invention.

FIG. 3 is a perspective view of a conventional light emitting and receiving integrated photosensor.

FIG. 4 is a perspective view of a conventional light emitting / receiving separation type optical sensor.

FIG. 5 shows a circuit configuration of light emission and light reception of an optical sensor, (a) shows a photo transistor as a light receiving element, and
(B) is a circuit diagram using a photodiode as a light receiving element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light emitting part 2 Light receiving part 3 Emitted light 4 Reflected light 5 Exterior 6 Fixing member 7 Air blowing amount adjusting device 8 Compressed air tube 9 Code 10 Blowing air 16 Front surface 17 Rear surface 20 Object to be measured 30 Conveyor 31 Conveyor stand 40 Transistor Tr 42 Photo Transistor PTr 43 Light emitting diode LED 44 Photodiode PD 45 Resistor Re 46 Resistor Rb 47 Resistor Ra 48 Terminal

Continuation of front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location // G01V 8/12

Claims (2)

[Claims] 1. An optical sensor having a light emitting portion and a light receiving portion as a unit, wherein a hollow exterior covering one end of the light emitting portion and the light receiving portion is provided, and further, compressed air is provided in the hollow portion of the exterior. An integrated dust-prevention type optical sensor characterized in that a device for introducing the above is set on the wall surface of the exterior, and the introduced compressed air is blown out from the opening. 2. An optical sensor comprising a pair of devices separated into a light emitting portion and a light receiving portion, wherein a hollow exterior covering at least one of the light emitting portion and the light receiving portion of each device is provided, and A separate dust adhesion preventing optical sensor, characterized in that a device for introducing compressed air into the hollow portion of the exterior is set on a side surface of the exterior, and the introduced compressed air is blown out from an opening.